Longitudinal study of humoral immunity against SARS-CoV-2 of health professionals in Brazil: the impact of booster dose and reinfection on antibody dynamics.

Introduction: The pandemic caused by SARS-CoV-2 has had a major impact on health systems. Vaccines have been shown to be effective in improving the clinical outcome of COVID-19, but they are not able to fully prevent infection and reinfection, especially that caused by new variants. Methods: Here, we tracked for 450 days the humoral immune response and reinfection in 52 healthcare workers from Brazil. Infection and reinfection were confirmed by RT-qPCR, while IgM and IgG antibody levels were monitored by rapid test. Results: Of the 52 participants, 19 (36%) got reinfected during the follow-up period, all presenting mild symptoms. For all participants, IgM levels dropped sharply, with over 47% of them becoming seronegative by the 60th day. For IgG, 90% of the participants became seropositive within the first 30 days of follow-up. IgG antibodies also dropped after this period reaching the lowest level on day 270 (68.5 ± 72.3, p<0.0001). Booster dose and reinfection increased the levels of both antibodies, with the interaction between them resulting in an increase in IgG levels of 130.3 arbitrary units. Conclusions: Overall, our data indicate that acquired humoral immunity declines over time and suggests that IgM and IgG antibody levels are not associated with the prevention of reinfection.

Molecular detection of omicron SARS-CoV-2 variant is achieved by RT-LAMP despite genomic mutations.

BACKGROUND: Severe acute respiratory syndrome coronavirus (SARS-CoV-2) omicron variant was first detected in South Africa in November 2021. Since then, the number of cases due to this variant increases enormously every day in different parts of the world. Mutations within omicron genome may impair the molecular detection resulting in false negative results during Coronavirus disease 19 (COVID-19) diagnosis. OBJECTIVES: To verify if colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) targeting N and E genes would work efficiently to detect omicron SARS-CoV-2 variant and its sub-lineages. METHODS: SARS-CoV-2 reverse transcription quantitative polymerase chain reaction (RT-qPCR) positive samples were sequenced by next generation DNA sequencing. The consensus sequences generated were submitted to Pangolin tool for SARS-CoV-2 lineage identification. RT-LAMP reactions were performed at 65ºC/30 min targeting N and E. FINDINGS: SARS-CoV-2 omicron can be detected by RT-LAMP targeting N and E genes despite the genomic mutation of this more transmissible lineage. Omicron SARS-CoV-2 sub-lineages were tested and efficiently detected by RT-LAMP. We demonstrated that this test is very sensitive in detecting omicron variant, with LoD as low as 0.4 copies/µL. MAIN CONCLUSIONS: Molecular detection of omicron SARS-CoV-2 variant and its sub-lineages can be achieved by RT-LAMP despite the genomic mutations as a very sensitive surveillance tool for COVID-19 molecular diagnosis.

Equine Infectious Anemia Virus (EIAV): Evidence of Circulation in Donkeys from the Brazilian Northeast Region.

Equine infectious anemia (EIA) is listed by the World Organization for Animal Health (OIE) as one of the equine diseases that must be notified. No effective treatment or vaccine is available. EIA control is based on segregation and euthanasia of positive equids. The disease is caused by the equine infectious anemia virus (EIAV), a member of the genus Lentivirus of the Retroviridae family. Despite the importance of this disease in equids, EIA has been poorly studied in donkeys (Equus asinus). We evaluate the sanitary conditions related to EIAV in donkeys from a shelter of abandoned animals captured on the roads of the Ceará. A total of 124 donkeys were randomly selected, and three horses lived at the same shelter. The animals were clinically evaluated, and a group of the 20 animals was submitted to hematological tests. Three diagnostic tests for EIA were used, agar gel immunodiffusion (AGID), enzyme-linked immunosorbent assay (ELISA) using EIAV recombinant protein gp90 (rgp90) and recombinant protein p26 (rp26) ELISA, and polymerase chain reaction (PCR) for detection of the EIAV tat-gag gene. From the donkeys, only 1 animal was positive using AGID 0.81% (1/124), compared to 21.8% (27/124) in the rgp90 and 10.5% (13/124) in the rp26 ELISA. Proviral DNA was detected by PCR tat-gag in 8.8% (11/124), and phylogenetic analysis confirms that the EIAV sequences of donkeys from the Brazilian Northeast grouped with Pantanal Brazilian sequences. Thus, in light of the results, we conclude that donkeys are carriers of EIAV and could be sources of infection.

Molecular detection of omicron SARS-CoV-2 variant is achieved by RT-LAMP despite genomic mutations

BACKGROUND Severe acute respiratory syndrome coronavirus (SARS-CoV-2) omicron variant was first detected in South Africa in November 2021. Since then, the number of cases due to this variant increases enormously every day in different parts of the world. Mutations within omicron genome may impair the molecular detection resulting in false negative results during Coronavirus disease 19 (COVID-19) diagnosis. OBJECTIVES To verify if colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) targeting N and E genes would work efficiently to detect omicron SARS-CoV-2 variant and its sub-lineages. METHODS SARS-CoV-2 reverse transcription quantitative polymerase chain reaction (RT-qPCR) positive samples were sequenced by next generation DNA sequencing. The consensus sequences generated were submitted to Pangolin tool for SARS-CoV-2 lineage identification. RT-LAMP reactions were performed at 65ºC/30 min targeting N and E. FINDINGS SARS-CoV-2 omicron can be detected by RT-LAMP targeting N and E genes despite the genomic mutation of this more transmissible lineage. Omicron SARS-CoV-2 sub-lineages were tested and efficiently detected by RT-LAMP. We demonstrated that this test is very sensitive in detecting omicron variant, with LoD as low as 0.4 copies/µL. MAIN CONCLUSIONS Molecular detection of omicron SARS-CoV-2 variant and its sub-lineages can be achieved by RT-LAMP despite the genomic mutations as a very sensitive surveillance tool for COVID-19 molecular diagnosis.

Identification of large genetic variations in the equine infectious anemia virus tat-gag genomic region.

The aetiological agent of equine infectious anaemia (EIA) is the retrovirus equine infectious anemia virus (EIAV) that infects all members of the Equidae family. The EIA is widely disseminated in the Brazilian territory with a high seroprevalence in the Brazilian Pantanal and is mainly diagnosed using agar gel immunodiffusion (AGID). There are few complete EIAV genome sequences available in GenBank, which had an impact on molecular detection studies. In this study, we conducted molecular detection and sequencing of EIAV proviral DNA from Brazilian horses. We analysed the genomic region from exon 1 of tat to gag (tat-gag). Comparative serological tests, comprising AGID and two enzyme-linked immunosorbent assays (ELISAs), were also conducted. Of the 133 samples, 58 were positive in the tat-gag PCR, and 49 nucleotide sequences of 272 bp were obtained. Using this developed tat-gag PCR EIAV proviral DNA was detected in 7% of the AGID-negative samples and 26% of the AGID-negative samples were positive in at least one of the ELISA tests used. Using phylogenetic analysis, the Brazilian Pantanal EIAV sequences grouped in a different clade of EIAV sequences from other countries. Thus, the EIAV sequences can contribute to the knowledge of the tat-gag genomic region in the circulating viruses in the Brazilian Pantanal, in addition to providing new information about the genetic diversity. In addition, the serological results demonstrate the greater sensitivity of the ELISAs used in this study compared to AGID for EIA diagnosis.

Equine infectious anemia virus in naturally infected horses from the Brazilian Pantanal.

Equine infectious anemia (EIA) has a worldwide distribution, and is widespread in Brazil. The Brazilian Pantanal presents with high prevalence comprising equine performance and indirectly the livestock industry, since the horses are used for cattle management. Although EIA is routinely diagnosed by the agar gel immunodiffusion test (AGID), this serological assay has some limitations, so PCR-based detection methods have the potential to overcome these limitations and act as complementary tests to those currently used. Considering the limited number of equine infectious anemia virus (EIAV) sequences which are available in public databases and the great genome variability, studies of EIAV detection and characterization molecular remain important. In this study we detected EIAV proviral DNA from 23 peripheral blood mononuclear cell (PBMCs) samples of naturally infected horses from Brazilian Pantanal using a semi-nested-PCR (sn-PCR). The serological profile of the animals was also evaluated by AGID and ELISA for gp90 and p26. Furthermore, the EIAV PCR amplified DNA was sequenced and phylogenetically analyzed. Here we describe the first EIAV sequences of the 5' LTR of the tat gene in naturally infected horses from Brazil, which presented with 91% similarity to EIAV reference sequences. The Brazilian EIAV sequences also presented variable nucleotide similarities among themselves, ranging from 93,5% to 100%. Phylogenetic analysis showed that Brazilian EIAV sequences grouped in a separate clade relative to other reference sequences. Thus this molecular detection and characterization may provide information about EIAV circulation in Brazilian territories and improve phylogenetic inferences.

Cross-sectional study involving healthcare professionals in a Vaccinia virus endemic area.

Orthopoxviruses (OPV) are emerging viruses with great importance in human and veterinary medicine, such as Vaccinia virus (VACV), which causes outbreaks of bovine vaccinia (BV) in South America. The clinical aspects of BV are similar to other vesicular infections, complicating the clinical diagnosis. This cross-sectional study evaluated the knowledge of Healthcare Professionals about BV and revealed their unpreparedness about BV in a VACV hyper-endemic area in Brazil, highlighting the public health issues associated with VACV infections. This study presents an opportunity to discuss the importance of vaccination for healthcare professionals who work in areas of VACV circulation and brings an educational measure on VACV infections for health professionals around the world.

Detection of Vaccinia Virus in Dairy Cattle Serum Samples from 2009, Uruguay.

We detected orthopoxvirus in 28 of 125 serum samples collected during 2009 from cattle in Uruguay. Two samples were PCR-positive for vaccinia virus and had sequences similar to those for vaccinia virus associated with outbreaks in Brazil. Autochthonous circulation of vaccinia virus in Uruguay and other South American countries cannot be ruled out.

The detection of Vaccinia virus confirms the high circulation of Orthopoxvirus in buffaloes living in geographical isolation, Marajó Island, Brazilian Amazon.

In Brazil, serologic evidence of Orthopoxvirus (OPV) circulation showed positivity around 20% in cattle, humans, monkeys and rodents. Although OPV seropositivity has been described in buffalo herds in southeastern Brazil, no Vaccinia virus (VACV) (member of genus OPV) outbreaks in buffalo herds have been described in this country. This study aimed to investigate the detection of anti-OPV antibodies and to study the OPV genome in Brazilian buffalo herds. Our results demonstrated a high OPV seropositivity in buffalo herds on Marajó Island and molecular data confirmed the circulation of VACV. The geographical isolation conditionmight be a sine qua non condition to explain our results.